Perpetual calendar



FIG. 1 is a front elevational view of the perpetual calendar;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The ornamental design for a perpetual calendar, as shown and described.